Phylogenetic classification and species identification of dermatophyte strains based on DNA sequences of nuclear ribosomal internal transcribed spacer 1 regions.
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The mutual phylogenetic relationships of dermatophytes of the genera Trichophyton, Microsporum, and Epidermophyton were demonstrated by using internal transcribed spacer 1 (ITS1) region ribosomal DNA sequences. Trichophyton spp. and Microsporum spp. form a cluster in the phylogenetic tree with Epidermophyton floccosum as an outgroup, and within this cluster, all Trichophyton spp. except Trichophyton terrestre form a nested cluster (100% bootstrap support). Members of dermatophytes in the cluster of Trichophyton spp. were classified into three groups with ITS1 homologies, with each of them being a monophyletic cluster (100% bootstrap support). The Arthroderma vanbreuseghemii-Arthroderma simii group consists of A. vanbreuseghemii, A. simii, Trichophyton mentagrophytes isolates from humans, T. mentagrophytes var. quinckeanum, Trichophyton tonsurans, and Trichophyton schoenleinii. Arthroderma benhamiae, T. mentagrophytes var. erinacei, and Trichophyton verrucosum are members of the Arthroderma benhamiae group. Trichophyton rubrum and Trichophyton violaceum form the T. rubrum group. This suggests that these "species" of dermatophytes have been overclassified. The ITS1 sequences of 11 clinical isolates were also determined to identify the species, and all strains were successfully identified by comparison of their base sequences with those in the ITS1 DNA sequence database. (+info)
Antifungal susceptibility testing of dermatophytes: establishing a medium for inducing conidial growth and evaluation of susceptibility of clinical isolates.
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A standardized reference method for dermatophyte in vitro susceptibility testing is lacking. In a previous study, Norris et al. (H. A. Norris, B. E. Elewski, and M. A. Ghannoum, J. Am. Acad. Dermatol. 40(6, part 2):S9-S13) established the optimal medium and other growth variables. However, the earlier study did not address two issues: (i) selection of an optimal medium for conidial formation by dermatophytes and (ii) validation of the method with a large number of dermatophytes. The present study addresses these two points. To select which agar medium best supported conidial growth, representative isolates of dermatophytes were grown on different agars. Preliminary experiments showed that only oatmeal cereal agar supported the production of conidia by Trichophyton rubrum. We tested the abilities of 251 T. rubrum isolates to form conidia using three different cereal agars and potato dextrose agar. Overall, oatmeal cereal and rice agar media were comparable in their abilities to support T. rubrum conidial growth. Next, we used the oatmeal cereal agar for conidial formation along with the optimal conditions for dermatophyte susceptibility testing proposed by Norris et al. and determined the antifungal susceptibilities of 217 dermatophytes to fluconazole, griseofulvin, itraconazole, and terbinafine. Relative to the other agents tested, terbinafine possessed the highest antifungal activity against all of the dermatophytes. The mean +/- standard error of the mean MICs of fluconazole, itraconazole, terbinafine, and griseofulvin were 2.07 +/- 0.29, 0.13 +/- 0.01, 0.002 +/- 0.0003, and 0.71 +/- 0.05 microgram/ml, respectively. This study is the first step in the identification of optimal conditions that could be used for the standardization of the antifungal susceptibility testing method for dermatophytes. Inter- and intralaboratory agreement as well as clinical correlations need to be established. (+info)
Isolation of dermatophytes, Candida species and systemic fungi from dermatologic specimens in Montreal, 1963 to 1973.
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Of 10 057 specimens of scrapings from skin, nails and scalp examined for dermatophytes, yeasts, pityriasis versicolor and systemic mycoses between 1963 and 1973, 30.4 percent were positive for fungi. Skin produced the highest proportion (68.6 percent) of positive scrapings, scalp the lowest (4.2 percent). Trichophyton rubrum was the predominant species (23.6 percent); of lesser prevalence were Microsporum canis (9.3 percent), T. mentagrophytes (8.4 percent) and Epidermophyton floccosum (4.8 percent). Double infections were encountered on 102 occasions; T. rubrum and Candida parapsilosis were the most frequent cohabiting species. The introduction in 1966 of periodic acid-Schiff staining for routine examination of scrapings resulted in better diagnostic results, particularly in the case of culturally nonproductive specimens and cases of pityriasis versicolor. Blastomyces dermatitidis and Cryptococcus neoformans were isolated from two patients in the course of routine investigation for dermatophytes. (+info)
Application of PCR to distinguish common species of dermatophytes.
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This report describes the application of PCR fingerprinting for the identification of species and varieties of common dermatophytes and related fungi utilizing as a single primer the simple repetitive oligonucleotide (GACA)(4). The primer was able to amplify all the strains, producing species-specific profiles for Microsporum canis, Microsporum gypseum, Trichophyton rubrum, Trichophyton ajelloi, and Epidermophyton floccosum. Intraspecific variability was not observed for these species. Instead, three different profiles were observed in the Trichophyton mentagrophytes group. (+info)
Use of the sensititre colorimetric microdilution panel for antifungal susceptibility testing of dermatophytes.
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The Sensititre YeastOne antifungal panel was used to test 49 dermatophytes belonging to the species Epidermophyton floccosum, Microsporum gypseum, Microsporum canis, Trichophyton tonsurans, Trichophyton rubrum, and Trichophyton mentagrophytes. The MICs of four antifungals obtained with the Sensititre YeastOne antifungal panel were compared with those obtained by the reference NCCLS microdilution method. The levels of agreement between the two methods (+info)
A comparative survey of serum androgenic hormones levels between male patients with dermatophytosis and normal subjects.
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Fungal growth can be influenced by human physiological mediators such as androgenic hormones. The aim of this study was to investigate a possible relationship between androgenic hormones and susceptibility to dermatophytosis. To this purpose we measured the levels of testosterone, androstendione, and dehydroepianderosterone sulfate (DHEA-S) in 60 male patients with dermatophytosis due to Epidermophyton floccosum and Trichophyton rubrum by enzyme link immunoassay. Serum testosterone concentration was found to be significantly lower in patients with E. floccosum than in healthy subjects. No significant differences in androstendione and DHEA-S levels were noted between the patients and the healthy individuals. The results showed that testosterone concentration can be considered a predisposing factor for tinea cruris infection. (+info)
Tinea unguium in the north-west of Iran (1996-2004).
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Tinea unguium is a common mycosis in many part of the world including Iran. The prevalence of this mycosis varied depending on time, health level and geographical location. To stabilise the etiological, epidemiological and risk factors of tinea unguium in North-west Iran, a study of patients with suspected dermatophyte infections of their nails was carried out between 1996 and 2004. During this study 590 (354 females and 236 males) patients with clinical presentation of fungal infection in fingernails, toenails or in the both sites, were investigated using direct microscopy and culture of clinical samples. Tinea unguium was documented in 41 cases (7%) and among positive cases, 16 cases (39% total positive cases) were female and 25 cases (61% total positive cases) were male. Seventeen patients (41% total positive cases) had tinea unguium in their finger nails and 24 patients (59% total positive cases) had infection in their toe nails. According to the isolated etiologic agent, 66% (19 cases) of tinea unguium infections were caused by zoophilic drematophytes, 31% (9 cases) were caused by anthropophilic drematophytes and 3% (1 case) were caused by geophilic dermatophytes. With regard of sex, tinea unguium did not show a significant difference. The highest prevalence of tinea unguium was found in patients between 11 and 40 years of age. In conclusion the current results identified the etiological agents and epidemiological aspects of tinea unguium in North-west Iran. Tinea unguium in this region is associated with animal husbandry and direct or indirect contact with their products (wool, leather). (+info)
Single-step PCR using (GACA)4 primer: utility for rapid identification of dermatophyte species and strains.
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